Thu0055 tpl2 Inhibition Suppresses Mek-Erk Inflammatory Signaling and Proinflammatory Cytokine Production in Primary Human Monocytes

Abstract

BackgroundTumor progression locus 2 (TPL2, also known as MAP3K8) is a mitogen-activated protein kinase kinase kinase and the primary regulator of ERK-mediated gene transcription downstream of multiple proinflammatory stimuli including bacterial products (eg, LPS and bacterial peptidoglycans), damage-associated molecular patterns (DAMPs), TNFα, and IL-1β.1 Dysregulated signaling downstream of these inflammatory signals can drive uncontrolled immune cell activation and inflammation, which is associated with multiple chronic inflammatory and autoimmune diseases. As such, TPL2 inhibition represents a strategy to modulate inflammation in a variety of disease settings.ObjectivesWe evaluated the effect of a highly selective TPL2 inhibitor on inflammatory signaling and cytokine production in LPS and TNFα-stimulated primary human monocytes.MethodsMonocytes were precultured with a TPL2 inhibitor and stimulated with LPS or TNFα, and phosphosignaling and cytokine production were then evaluated at 30 minutes and 4 hours poststimulation. A431 cells (human epidermoid carcinoma cell line) were stimulated with TNFα or EGF and phospho–ERK was evaluated after 30 minutes.ResultsTPL2 inhibition selectively inhibited LPS and TNFα-stimulated phosphorylation of TPL2, MEK, and ERK, with little to no inhibition of phosphorylated p38, JNK, or p65 observed. TPL2 inhibition similarly inhibited both the RNA production and secretion of TNFα, IL-1β, IL-6, and IL-8 following LPS stimulation in primary human monocytes. To confirm TPL2 requirement for inflammatory, but not Ras-mediated (growth factor stimulated) ERK signaling, A431 cells were stimulated with either TNFα or EGF. Although TPL2 inhibition reduced TNFα-stimulated pERK, no effect on ERK activation downstream of EGF was observed.ConclusionThis work demonstrates the selective effects of TPL2 inhibition on ERK-mediated signaling and proinflammatory cytokine gene transcription in primary human monocytes and highlights the potential for TPL2 inhibition to treat diseases associated with dysregulated inflammatory signaling and chronic inflammation.Reference[1] Gantke T, Sriskantharajah S, Ley S. Cell Res. 2011;21:131-145.Disclosure of InterestsMatthew R. Warr Shareholder of: Gilead Sciences, Inc., Employee of: Gilead Sciences, Inc., Angie Hammond Grant/research support from: Gilead Sciences, Inc., Employee of: Gilead Sciences, Inc., Grace Park Grant/research support from: Gilead Sciences, Inc., Employee of: Gilead Sciences, Inc., Nathan Wright Shareholder of: Gilead Sciences, Inc., Employee of: Gilead Sciences, Inc., James Taylor Grant/research support from: Gilead Sciences, Inc., Employee of: Gilead Sciences, Inc.

New Druggable Targets for Rheumatoid Arthritis Based on Insights From Synovial Biology

“…This feature, not found in other human kinases, exposes a deeper flexible pocket which can be exploited for selective drug design ( 58 ), wherein traditional ATP-mimetic scaffolds may be extended for extra hydrophobic and hydrogen bonding interactions ( Figure 5B ). Although MAP3K8 is a relatively newer target for RA with few SAR inhibitors reported in preclinical studies ( 58 , 138 ), a specific inhibitor, GS-4875, is advancing in clinical animal studies for multiple inflammatory diseases ( 139 ).…”